docs(docs): adding CI from docs-template to standardise documentation across the scicatproject

[LAShemilt]

docs: adding CI from docs-template to standardise documentation across the scicatproject.

Description

This PR removes the old CI for docs described in docs.yml to inherit the CI from docs-template https://github.com/SciCatProject/docs-template. This will apply styling and branding that is consistent across the project.

Motivation

To improve the SciCat documentation and to give constributors a place to add documentation directly to the microservices.

Changes:

• added mkdocs.yml that inherits the default from docs-template
• added publish-docs.yml workflow that uses the CI workflow
• added the README.md as an index.md in the docs